Video playback stutters (frame drops) with hardware acceleration on NVIDIA dGPUs (RTX 5090 / RTX 4060); works fine on iGPUs

Video playback stutters (frame drops) with hardware acceleration on NVIDIA dGPUs (RTX 5090 / RTX 4060); works fine on iGPUs

System Details

• OS: Windows 11
• Thorium Version: https://github.com/gz83/thorium/releases/tag/M152.0.7977.55 Windows-AVX512 https://github.com/gz83/thorium/releases/tag/M151.0.7922.72 Windows-AVX512
• NVIDIA Driver: GeForce Game Ready 616.86
• AMD Driver: Adrenalin Edition 26.8.1

Problem GPU-accelerated video playback (hardware acceleration) stutters (frame drops) on both NVIDIA GPUs. Reproduced on two different machines (one desktop, one laptop); in each one the integrated GPU works normally while the dGPU stutters:

• Machine 1 (desktop): Ryzen 9 9850X3D + RTX 5090
  • RTX 5090: video stutters on both M152.0.7977.55 and M151.0.7922.72 AVX512
  • Radeon iGPU (9850X3D): hardware acceleration works fine
• Machine 2 (laptop): Ryzen 7 7940HS + RTX 4060 Laptop GPU
  • RTX 4060 Laptop GPU: video stutters on both versions
  • Radeon 780M iGPU (7940HS): hardware acceleration works fine

Steps to Reproduce

1. Use the NVIDIA card as the rendering GPU and enable hardware acceleration.
2. Play any video — stuttering (frame drops) occurs.
3. Repeat the same steps with the integrated GPU instead → smooth playback.

Reproduced on:

• Bilibili (bilibili.com) videos, and local videos opened via file://
• All codecs tested: AV1, HEVC, AVC
• Symptom: visible frame drops / stutters, not a freeze or black video

Additional Info

• The same videos play smoothly on the same machines with:
  • Google Chrome (official release)
  • Microsoft Edge 152.4191.66
  • Chromium 153.0.7993.0 while the stutters only appear in Thorium — the issue appears specific to the Thorium build rather than the GPU, codec, or driver.

Note: This report was drafted with Qwen3.8-27B and manually reviewed.